Memory having a static cache and a dynamic cache

ABSTRACT

The present disclosure includes memory having a static cache and a dynamic cache. A number of embodiments include a memory, wherein the memory includes a first portion configured to operate as a static single level cell (SLC) cache and a second portion configured to operate as a dynamic SLC cache when the entire first portion of the memory has data stored therein.

PRIORITY INFORMATION

This application is a Continuation of U.S. application Ser. No.14/735,498, filed Jun. 10, 2015, the specification of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to semiconductor memory andmethods, and more particularly, to memory having a static cache and adynamic cache.

BACKGROUND

Memory devices are typically provided as internal, semiconductor,integrated circuits and/or external removable devices in computers orother electronic devices. There are many different types of memoryincluding volatile and non-volatile memory. Volatile memory can requirepower to maintain its data and can include random-access memory (RAM),dynamic random access memory (DRAM), and synchronous dynamic randomaccess memory (SDRAM), among others. Non-volatile memory can retainstored data when not powered and can include NAND flash memory, NORflash memory, phase change random access memory (PCRAM), resistiverandom access memory (RRAM), and magnetic random access memory (MRAM),among others.

Memory devices can be combined together to form a solid state drive(SSD). An SSD can include non-volatile memory (e.g., NAND flash memoryand/or NOR flash memory), and/or can include volatile memory (e.g., DRAMand/or SRAM), among various other types of non-volatile and volatilememory. Flash memory devices can include memory cells storing data in acharge storage structure such as a floating gate, for instance, and maybe utilized as non-volatile memory for a wide range of electronicapplications. Flash memory devices typically use a one-transistor memorycell that allows for high memory densities, high reliability, and lowpower consumption.

Memory cells in an array architecture can be programmed to a target(e.g., desired) state. For instance, electric charge can be placed on orremoved from the charge storage structure (e.g., floating gate) of amemory cell to program the cell to a particular data state. The storedcharge on the charge storage structure of the memory cell can indicate athreshold voltage (Vt) of the cell, and the state of the cell can bedetermined by sensing the stored charge (e.g., the Vt) of the cell.

For example, a single level cell (SLC) can be programmed to a targetedone of two different data states, which can be represented by the binaryunits 1 or 0. Some flash memory cells can be programmed to a targetedone of more than two data states (e.g., 1111, 0111, 0011, 1011, 1001,0001, 0101, 1101, 1100, 0100, 0000, 1000, 1010, 0010, 0110, and 1110).Such cells may be referred to as multi state memory cells, multiunitcells, or multilevel cells (MLCs). MLCs can provide higher densitymemories without increasing the number of memory cells since each cellcan represent more than one digit (e.g., more than one bit).

In some instances, caching (e.g., caching schemes) can be utilized inmemory (e.g., SSDs) to increase the performance (e.g., speed) and/orendurance (e.g., lifetime) of the memory. For example, a portion (e.g.,a number of blocks) of a memory can be utilized as a cache totemporarily store data that may be used again in subsequent program(e.g., write) and/or sense (e.g., read) operations performed on thememory.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of a portion of a memory array having anumber of physical blocks in accordance with a number of embodiments ofthe present disclosure.

FIG. 2 is a functional block diagram of a computing system including anapparatus in the form of a memory device in accordance with a number ofembodiments of the present disclosure.

FIG. 3 illustrates a diagram of a memory having a static cache and adynamic cache in accordance with a number of embodiments of the presentdisclosure.

FIG. 4 illustrates a method of operating memory in accordance with anumber of embodiments of the present disclosure.

DETAILED DESCRIPTION

The present disclosure includes memory having a static cache and adynamic cache. A number of embodiments include a memory, wherein thememory includes a first portion configured to operate as a static singlelevel cell (SLC) cache and a second portion configured to operate as adynamic SLC cache when the entire first portion of the memory has datastored therein.

Caching schemes (e.g., memory having a static cache and a dynamic cache)in accordance with the present disclosure can increase the performance(e.g., increase the speed, increase the reliability, and/or decrease thepower consumption) and/or increase the endurance (e.g., increase thelifetime) of the memory, among other benefits. For example, cachingschemes in accordance with the present disclosure can increase theperformance of the memory early in (e.g., at the beginning of) thelifetime of the memory, when large program operations, such as operatingsystem (OS) and/or program (e.g., game) installations, are likely to beperformed on the memory. Further, caching schemes in accordance with thepresent disclosure can ensure that the endurance of the memory isprotected during periods of heavy use of the memory (e.g., periods whena large number of program and/or erase operations are being performed onthe memory).

Further, caching schemes in accordance with the present disclosure canincrease the performance and/or endurance of the memory as compared withprevious caching approaches. For example, a number of previous cachingapproaches may utilize only a single portion of the memory to operate asa static (e.g., dedicated) cache in SLC mode. However, when this entireportion of the memory has data stored therein (e.g., when the entirecache becomes full), the performance of the memory may sharply decrease.As an additional example, a number of previous caching approaches mayutilize the entire memory to operate as dynamic cache in SLC mode.However, utilizing the entire memory in such a manner can result instress on the memory cells due to, for example, the mixed modeutilization between various bits per cell configuration, which mayreduce the endurance of the memory.

As used herein, “a number of” something can refer to one or more suchthings. For example, a number of memory cells can refer to one or morememory cells. Additionally, the designators “N”, “B”, “R”, and “S”, asused herein, particularly with respect to reference numerals in thedrawings, indicates that a number of the particular feature sodesignated can be included with a number of embodiments of the presentdisclosure.

The figures herein follow a numbering convention in which the firstdigit or digits correspond to the drawing figure number and theremaining digits identify an element or component in the drawing.Similar elements or components between different figures may beidentified by the use of similar digits. For example, 210 may referenceelement “10” in FIG. 2, and a similar element may be referenced as 310in FIG. 3.

FIG. 1 illustrates a diagram of a portion of a memory array 100 having anumber of physical blocks in accordance with a number of embodiments ofthe present disclosure. Memory array 100 can be, for example, a NANDflash memory array. However, embodiments of the present disclosure arenot limited to a particular type of memory or memory array. For example,memory array 100 can be a DRAM array, an RRAM array, or a PCRAM array,among other types of memory arrays. Further, although not shown in FIG.1, memory array 100 can be located on a particular semiconductor diealong with various peripheral circuitry associated with the operationthereof.

As shown in FIG. 1, memory array 100 has a number of physical blocks116-0 (BLOCK 0), 116-1 (BLOCK 1), . . . , 116-B (BLOCK B) of memorycells. The memory cells can be single level cells and/or multilevelcells such as, for instance, triple level cells (TLCs) or quadruplelevel cells (QLCs). As an example, the number of physical blocks inmemory array 100 may be 128 blocks, 512 blocks, or 1,024 blocks, butembodiments are not limited to a particular multiple of 128 or to anyparticular number of physical blocks in memory array 100. A first numberof blocks 116-0, 116-1, . . . , 116-B can be configured to operate as astatic SLC cache, and a second number of blocks 116-0, 116-1, . . . ,116-B can be configured to operate as a dynamic SLC cache, as will befurther described herein.

A number of physical blocks of memory cells (e.g., blocks 116-0, 116-1,. . . , 116-B) can be included in a plane of memory cells, and a numberof planes of memory cells can be included on a die. For instance, in theexample shown in FIG. 1, each physical block 116-0, 116-1, . . . , 116-Bcan be part of a single die. That is, the portion of memory array 100illustrated in FIG. 1 can be die of memory cells.

As shown in FIG. 1, each physical block 116-0, 116-1, . . . , 116-Bcontains a number of physical rows (e.g., 120-0, 120-1, . . . , 120-R)of memory cells coupled to access lines (e.g., word lines). The numberof rows (e.g., word lines) in each physical block can be 32, butembodiments are not limited to a particular number of rows 120-0, 120-1,. . . , 120-R per physical block. Further, although not shown in FIG. 1,the memory cells can be coupled to sense lines (e.g., data lines and/ordigit lines).

As one of ordinary skill in the art will appreciate, each row 120-0,120-1, . . . , 120-R can include a number of pages of memory cells(e.g., physical pages). A physical page refers to a unit of programmingand/or sensing (e.g., a number of memory cells that are programmedand/or sensed together as a functional group). In the embodiment shownin FIG. 1, each row 120-0, 120-1, . . . , 120-R comprises one physicalpage of memory cells. However, embodiments of the present disclosure arenot so limited. For instance, in a number of embodiments, each row cancomprise multiple physical pages of memory cells (e.g., one or more evenpages of memory cells coupled to even-numbered bit lines, and one ormore odd pages of memory cells coupled to odd numbered bit lines).Additionally, for embodiments including multilevel cells, a physicalpage of memory cells can store multiple pages (e.g., logical pages) ofdata (e.g., an upper page of data and a lower page of data, with eachcell in a physical page storing one or more bits towards an upper pageof data and one or more bits towards a lower page of data).

A program operation (e.g., a write operation) can include applying anumber of program pulses (e.g., 16V-20V) to a selected word line inorder to increase the threshold voltage (Vt) of the selected cellscoupled to that selected word line to a desired program voltage levelcorresponding to a target (e.g., desired) data state. A sense operation,such as a read or program verify operation, can include sensing avoltage and/or current change of a sense line coupled to a selected cellin order to determine the data state of the selected cell.

In a number of embodiments of the present disclosure, and as shown inFIG. 1, a page of memory cells can comprise a number of physical sectors122-0, 122-1, . . . , 122-S (e.g., subsets of memory cells). Eachphysical sector 122-0, 122-1, . . . , 122-S of cells can store a numberof logical sectors of data (e.g., data words). Additionally, eachlogical sector of data can correspond to a portion of a particular pageof data. As an example, a first logical sector of data stored in aparticular physical sector can correspond to a logical sectorcorresponding to a first page of data, and a second logical sector ofdata stored in the particular physical sector can correspond to a secondpage of data. Each physical sector 122-0, 122-1, . . . , 122-S, canstore system and/or user data, and/or can include overhead data, such aserror correction code (ECC) data, logical block address (LBA) data, andrecurring error data.

Logical block addressing is a scheme that can be used by a host foridentifying a logical sector of data. For example, each logical sectorcan correspond to a unique logical block address (LBA). Additionally, anLBA may also correspond to a physical address. A logical sector of datacan be a number of bytes of data (e.g., 256 bytes, 512 bytes, or 1,024bytes). However, embodiments are not limited to these examples.

It is noted that other configurations for the physical blocks 116-0,116-1, . . . , 116-B, rows 120-0, 120-1, . . . , 120-R, sectors 122-0,122-1, . . . , 122-S, and pages are possible. For example, rows 120-0,120-1, . . . , 120-R of physical blocks 116-0, 116-1, . . . , 116-B caneach store data corresponding to a single logical sector which caninclude, for example, more or less than 512 bytes of data.

FIG. 2 is a functional block diagram of a computing system 201 includingan apparatus in the form of a memory device 204 in accordance with anumber of embodiments of the present disclosure. As used herein, an“apparatus” can refer to, but is not limited to, any of a variety ofstructures or combinations of structures, such as a circuit orcircuitry, a die or dice, a module or modules, a device or devices, or asystem or systems, for example.

Memory device 204 can be, for example, a solid state drive (SSD). In theembodiment illustrated in FIG. 2, memory device 204 includes a physicalhost interface 206, a number of memories 210-1, 210-2, . . . , 210-N(e.g., solid state memory devices), and a controller 208 (e.g., an SSDcontroller) coupled to physical host interface 206 and memories 210-1,210-2, . . . , 210-N.

Memories 210-1, 210-2, . . . , 210-N can include, for example, a numberof non-volatile memory arrays (e.g., arrays of non-volatile memorycells). For instance, memories 210-1, 210-2, . . . , 210-N can include anumber of memory arrays analogous to memory array 100 previouslydescribed in connection with FIG. 1.

Physical host interface 206 can be used to communicate informationbetween memory device 204 and another device such as a host 202. Host202 can include a memory access device (e.g., a processor). One ofordinary skill in the art will appreciate that “a processor” can intenda number of processors, such as a parallel processing system, a numberof coprocessors, etc. Example hosts can include personal laptopcomputers, desktop computers, digital cameras, digital recording andplayback devices, mobile (e.g., smart) phones, PDAs, memory cardreaders, interface hubs, and the like.

Physical host interface 206 can be in the form of a standardizedphysical interface. For example, when memory device 204 is used forinformation storage in computing system 201, physical host interface 206can be a serial advanced technology attachment (SATA) physicalinterface, a peripheral component interconnect express (PCIe) physicalinterface, or a universal serial bus (USB) physical interface, amongother physical connectors and/or interfaces. In general, however,physical host interface 206 can provide an interface for passingcontrol, address, information (e.g., data), and other signals betweenmemory device 204 and a host (e.g., host 202) having compatiblereceptors for physical host interface 206.

Controller 208 can include, for example, control circuitry and/or logic(e.g., hardware and firmware). Controller 208 can be included on thesame physical device (e.g., the same die) as memories 210-1, 210-2, . .. , 210-N. For example, controller 208 can be an application specificintegrated circuit (ASIC) coupled to a printed circuit board includingphysical host interface 206 and memories 210-1, 210-2, . . . , 210-N.Alternatively, controller 208 can be included on a separate physicaldevice that is communicatively coupled to the physical device thatincludes memories 210-1, 210-2, . . . , 210-N. In a number ofembodiments, components of controller 208 can be spread across multiplephysical devices (e.g., some components on the same die as the memory,and some components on a different die, module, or board) as adistributed controller.

Controller 208 can communicate with memories 210-1, 210-2, . . . , 210-Nto sense (e.g., read), program (e.g., write), and/or erase information,among other operations. Controller 208 can have circuitry that may be anumber of integrated circuits and/or discrete components. In a number ofembodiments, the circuitry in controller 208 may include controlcircuitry for controlling access across memories 210-1, 210-2, . . . ,210-N and/or circuitry for providing a translation layer between host202 and memory device 204.

Controller 208 can operate a dedicated region, such as a blockaddressing portion, of each respective memory 210-1, 210-2, . . . ,210-N as (e.g., configure a portion of each respective memory 210-1,210-2, . . . , 210-N to operate as) a static (e.g., dedicated) singlelevel cell (SLC) cache. That is, this portion of each respective memorycan be configured to operate as a static cache in SLC mode. This portionof each respective memory 210-1, 210-2, . . . , 210-N can be, forexample, a first plurality of blocks (e.g., physical blocks) of memorycells in each respective memory, as will be further described herein(e.g., in connection with FIG. 3), and may be referred to herein as afirst portion of the memory.

To ensure the highest possible endurance is available for the static SLCcache, the dedicated region (e.g., first portion) of each respectivememory can be configured to continuously operate in SLC mode as thestatic SLC cache for the entire lifetime of memory device 204, as SLCerase operations (e.g., erase operations performed in SLC mode) areorders of magnitude less destructive than MLC (e.g., TLC) eraseoperations. For example, in a number of embodiments, the memory cells ofthe first portion (e.g., the memory cells of the first plurality ofblocks) can be MLCs configured to operate in SLC mode, and in a numberof embodiments, the memory cells of the first portion can be SLCs. Inboth such embodiments, controller 208 can perform erase operations, aswell as program and sense operations, on the cells in SLC mode.

Controller 208 can operate a second portion of each respective memory210-1, 210-2, . . . , 210-N as (e.g., configure a second portion of eachrespective memory 210-1, 210-2, . . . , 210-N to operate as) a dynamicSLC cache when the entire first portion of each respective memory hasdata stored therein (e.g., when the first portion is full and/or whenhost 202 is attempting to program more data than may be stored in thefirst portion), and can operate the second portion of each respectivememory as (e.g., configure the second portion of each respective memoryto operate as) MLC memory (e.g., in MLC storage mode) when less than theentire first portion of each respective memory has data stored therein(e.g., when the first portion is not full). That is, the second portioncan be configured to operate as an overflow cache in SLC mode when theentire first portion (e.g., the entire static SLC cache) has data storedtherein, and operate as standard MLC memory (e.g., store data in MLCmode) when less than the entire first portion (e.g., less than theentire static SLC cache) has data stored therein. For instance, thesecond portion can operate as TLC or QLC memory when less than theentire first portion has data stored therein.

As used herein, MLC memory (e.g., MLCs) can refer to memory (e.g. memorycells) that can be programmed to a targeted one of more than two datastates (e.g., memory cells that can store two or more bits of data). Forexample, MLC memory can refer to memory cells that store two bits ofdata per cell, memory cells that store three bits of data per cell(e.g., TLCs), and/or memory cells that store four bits of data per cell(e.g., QLCs).

The second portion of each respective memory 210-1, 210-2, . . . , 210-Ncan be, for example, a second plurality of blocks (e.g., physicalblocks) of memory cells in each respective memory, as will be furtherdescribed herein (e.g., in connection with FIG. 3). Controller 208 canperform erase operations, as well as program and sense operations, onthe cells of the second portion in MLC mode.

The size of the second portion of each respective memory 210-1, 210-2, .. . , 210-N can correspond to the quantity of memory cells used by thatmemory to program data stored in the SLCs of the memory to the MLCs ofthe memory (e.g., to fold the SLC data to the MLCs). For example, thesize of the second portion can be the total size of the memory in targetdensity, minus the size of the first portion multiplied by the number ofbits per cell in the second portion (e.g., 3 if the second portion isconfigured to operate as TLC, 4 if the second portion is configured tooperate as QLC). Generally, the size of the first portion is small ascompared to the whole drive density. For example, for a memory whosetotal size (e.g., drive density) is 128 GB, the size of the firstportion may be 3 GB, and the size of the second portion would be thebalance (e.g., 128 GB-3 GB*x, where x is the number of bits per cell inthe second portion).

In a number of embodiments, the second portion of each respective memorymay only operate as a dynamic SLC cache (e.g., as an overflow cache inSLC mode) until up to a particular point in the lifetime of memorydevice 204. Upon that point being reached, controller 208 can operatethe second portion as MLC memory (e.g., in MLC storage mode). That is,upon the particular point in the lifetime of memory device 204 beingreached, controller 208 can disable (e.g., turn off) the overflow cachefunctionality of the second portion.

For example, controller 208 can operate the second portion of the memoryas MLC memory upon the quantity of program operations performed on thesecond portion meeting or exceeding a particular threshold (e.g., aparticular quantity of program operations), upon the quantity of eraseoperations performed on the second portion meeting or exceeding aparticular threshold (e.g., a particular quantity of erase operations),and/or upon the quantity of blocks in the second portion having datastored therein meeting or exceeding a particular threshold (e.g., aparticular quantity of blocks). As an additional example, controller 208can operate the second portion of the memory as MLC memory upon thequantity of blocks used by the memory to program data stored in the SLCsof the memory to the MLCs of the memory being equal to or greater thanthe quantity of blocks in the second portion.

The embodiment illustrated in FIG. 2 can include additional circuitry,logic, and/or components not illustrated so as not to obscureembodiments of the present disclosure. For example, memory device 204can include address circuitry to latch address signals provided over I/Oconnectors through I/O circuitry. Address signals can be received anddecoded by a row decoders and column decoders, to access memories 210-1,210-2, . . . , 210-N.

FIG. 3 illustrates a diagram of a memory 310 having a static cache and adynamic cache in accordance with a number of embodiments of the presentdisclosure. Memory 310 can be analogous to memories 210-1, 210-2, . . ., 210-N previously described in connection with FIG. 2. For example,memory 310 can include a number of memory arrays analogous to memoryarray 100 previously described in connection with FIG. 1.

As shown in FIG. 3, memory 310 can include a first portion 330-1, asecond portion 330-2, and a third portion 330-3. Each respective portion330-1, 330-2, 330-3 can include a number of blocks (e.g., physicalblocks) of memory cells (e.g., portion 330-1 can include a first numberof blocks, portion 330-2 can include a second number of blocks, andportion 330-3 can include a third number of blocks). For instance, inthe example illustrated in FIG. 3, portion 330-1 can include Block_0through Block_x-1 of memory 310, portion 330-2 can include Block_xthrough Block_y-1 of memory 310, and portion 330-3 can include Block_ythrough Block Max of memory 310.

As shown in FIG. 3, portion 330-1 can be smaller (e.g., include fewerblocks of memory cells) than portions 330-2 and 330-3. For example,portion 330-1 may include 2-3% of the total number of blocks in memory310. However, embodiments of the present disclosure are not limited to aparticular size for (e.g., number of blocks in) portions 330-1, 330-2,and 330-3. Further, although portions 330-1, 330-2, and 330-3 areillustrated as contiguous areas (e.g., as comprising contiguous blocksof memory cells) in FIG. 3, embodiments of the present disclosure arenot so limited (e.g., portions 330-1, 330-2, and/or 330-3 may comprisenon-contiguous blocks of memory cells).

As shown in FIG. 3, a different logical unit number (LUN) can beassociated with different sub-portions of portions 330-1, 330-2, and330-3. For instance, in the example illustrated in FIG. 3, LUN0 can beassociated with a first sub-portion of portions 330-1, 330-2, and 330-3,LUN1 can be associated with a second sub-portion of portions 330-1,330-2, and 330-3, and LUN2 can be associated with a third sub-portion ofportions 330-1, 330-2, and 330-3. Embodiments of the present disclosure,however, are not limited to this example.

The blocks of portion 330-1 can be configured to operate as a static(e.g., dedicated) single level cell (SLC) cache. That is, the blocks ofportion 330-1 can be configured to operate as a static cache in SLCmode. For example, the blocks of portion 330-1 can be configured tocontinuously operate in SLC mode as a static SLC cache for the entirelifetime of memory 310, in a manner analogous to that described inconnection with FIG. 2.

The blocks of portion 330-2 can be configured to operate as a dynamicSLC cache when all of the blocks of portion 330-1 have data storedtherein (e.g., when there are no free blocks in portion 330-1), and canbe configured to operate as MLC memory (e.g., in MLC storage mode) whenless than all of the blocks of portion 330-1 have data stored therein(e.g., when there are free blocks in portion 330-1). That is, the blocksof portion 330-2 can be configured to operate as an overflow cache inSLC mode when all the blocks of portion 330-1 have data stored therein,and to operate as standard MLC memory (e.g., store data in MLC mode)when less than all of the blocks of portion 330-1 have data storedtherein. In a number of embodiments, the blocks of portion 330-2 mayonly operate as a dynamic SLC cache (e.g., as an overflow cache in SLCmode) until up to a particular point in the lifetime of memory 310, in amanner analogous to that previously described in connection with FIG. 2.

The blocks of portion 330-3 can be configured to continuously operate asMLC memory (e.g., in MLC storage mode) for the entire lifetime of memory310. That is, the blocks of portion 330-3 may not be part of (e.g., usedfor) the static SLC cache or the dynamic SLC cache during operation ofmemory 310.

FIG. 4 illustrates a method 440 of operating memory in accordance with anumber of embodiments of the present disclosure. Method 440 can beperformed by, for example, controller 208 previously described inconnection with FIG. 2.

The memory can be, for example, memories 210-1, 210-2, . . . , 210-Npreviously described in connection with FIG. 2 and/or memory 310previously described in connection with FIG. 3. That is, the memory caninclude a first portion (e.g., a first number of blocks) configured tooperate as a static SLC cache, a second portion (e.g., a second numberof blocks) configured to operate as a dynamic SLC cache when the entirefirst portion has data stored therein and configured to operate as MLCmemory (e.g., in MLC storage mode) when less than the entire firstportion has data stored therein, and a third portion (e.g., a thirdnumber of blocks) configured to operate as MLC memory, as previouslydescribed herein.

At block 442, method 440 includes receiving a command to program (e.g.,write) data to the memory. The command can be received from, forexample, host 202 previously described in connection with FIG. 2.

At block 444, method 440 includes determining whether the entire firstportion of the memory (e.g., the entire static SLC cache) has datastored therein. Determining whether the entire static SLC cache has datastored therein can include, for example, determining whether there areany blocks in the static SLC cache that do not have data stored therein.For instance, determining whether the entire static SLC cache has datastored therein can include determining whether there are any blocks inthe static SLC cache that are erased (e.g., free) blocks. Thedetermination of whether the entire static SLC cache has data storedtherein can be made using, for example, a tracking table in the host orthe controller.

If it is determined that the entire static SLC cache does not have datastored therein (e.g., that there are blocks in the static SLC cache thatdo not have data stored therein), then the data received in the programcommand is programmed to (e.g., cached in) the static SLC cache at block446. For instance, the data may be programmed to the block(s) in thestatic SLC cache that do not have data stored therein (e.g., to the freeblock(s) in the static SLC cache).

If it is determined that the entire static SLC cache has data storedtherein (e.g., that there are no blocks in the static SLC cache that donot have data stored therein), it can then be determined whether thequantity of program or erase operations that have been performed on thesecond portion of the memory (e.g., on the dynamic SLC cache) meets orexceeds a particular threshold (e.g., a particular quantity) at block448. For instance, the controller can track (e.g., count) the quantityof program or erase operations performed on the dynamic SLC cache, andthe tracked quantity can be compared to the threshold to determinewhether the threshold has been met or exceeded.

If it is determined that the quantity of program or erase operationsperformed on the dynamic SLC cache meets or exceeds the particularthreshold, then data stored in the static SLC cache (e.g., in a block ofthe static SLC cache) can be programmed (e.g., folded) to MLC memory atblock 454. For example, data stored in the static SLC cache can beprogrammed to the MLC memory of the third portion of the memory. As anadditional example, the dynamic SLC cache can be configured to operateas MLC memory (e.g., the second portion of the memory can be convertedfrom the dynamic SLC cache to MLC memory), to which the data stored inthe static SLC cache can then be programmed.

The data received in the program command is then programmed to (e.g.,cached in) the static SLC cache at block 456. For instance, the data maybe programmed to the block of the static SLC cache in which the datafolded to the MLC memory was stored.

If it is determined that the quantity of program or erase operationsperformed on the dynamic SLC cache does not meet or exceed theparticular threshold, it can then be determined whether the quantity ofblocks in the dynamic

SLC cache having data stored therein meets or exceeds a particularthreshold (e.g., a particular quantity of blocks) at block 450. Thisdetermination can be made using, for example, a tracking table in thehost or the controller.

If it is determined that the quantity of blocks in the dynamic SLC cachehaving data stored therein meets or exceeds the particular threshold,method 440 can proceed to blocks 454 and 456, which have been previouslydescribed herein. If it is determined that the quantity of blocks in thedynamic SLC cache having data stored therein does not meet or exceed theparticular threshold, the data received in the program command can thenbe programmed to (e.g., cached in) the dynamic SLC cache at block 452.

Although specific embodiments have been illustrated and describedherein, those of ordinary skill in the art will appreciate that anarrangement calculated to achieve the same results can be substitutedfor the specific embodiments shown. This disclosure is intended to coveradaptations or variations of a number of embodiments of the presentdisclosure. It is to be understood that the above description has beenmade in an illustrative fashion, and not a restrictive one. Combinationof the above embodiments, and other embodiments not specificallydescribed herein will be apparent to those of ordinary skill in the artupon reviewing the above description. The scope of a number ofembodiments of the present disclosure includes other applications inwhich the above structures and methods are used. Therefore, the scope ofa number of embodiments of the present disclosure should be determinedwith reference to the appended claims, along with the full range ofequivalents to which such claims are entitled.

In the foregoing Detailed Description, some features are groupedtogether in a single embodiment for the purpose of streamlining thedisclosure. This method of disclosure is not to be interpreted asreflecting an intention that the disclosed embodiments of the presentdisclosure have to use more features than are expressly recited in eachclaim. Rather, as the following claims reflect, inventive subject matterlies in less than all features of a single disclosed embodiment. Thus,the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment.

1-20. (canceled)
 21. An apparatus, comprising: a memory, wherein thememory includes: a first portion configured to operate as a staticsingle level cell (SLC) cache; and a second portion configured tooperate as a dynamic SLC cache or multilevel cell (MLC) memory based onwhether a quantity of erase operations performed on the second portionof the memory meets or exceeds a particular threshold.
 22. The apparatusof claim 21, wherein the second portion of the memory is configured tooperate as MLC memory upon the quantity of erase operations performed onthe second portion of the memory meeting or exceeding the particularthreshold.
 23. The apparatus of claim 21, wherein the second portion ofthe memory is configured to operate as a dynamic SLC cache or MLC memorybased on whether a quantity program operations performed on the secondportion of the memory meets or exceeds a particular threshold.
 24. Theapparatus of claim 21, wherein the second portion of the memory isconfigured to operate as a dynamic SLC cache or MLC memory based onwhether the entire first portion of the memory has data stored therein.25. The apparatus of claim 21, wherein: the memory comprises a pluralityof blocks of memory cells; the first portion of the memory comprises afirst number of the plurality of blocks; and the second portion of thememory comprises a second number of the plurality of blocks.
 26. Theapparatus of claim 25, wherein the first number of the plurality ofblocks is smaller than the second number of the plurality of blocks. 27.A method of operating memory, comprising: configuring a first portion ofa memory to operate as a static single level cell (SLC) cache; andconfiguring a second portion of the memory to operate as a dynamic SLCcache or multilevel cell (MLC) memory based on whether a quantity ofblocks of memory cells in the second portion of the memory having datastored therein meets or exceeds a particular threshold.
 28. The methodof claim 27, wherein the method includes configuring the second portionof the memory to operate as MLC memory upon the quantity of blocks ofmemory cells in the second portion of the memory having data storedtherein meeting or exceeding the particular threshold.
 29. The method ofclaim 28, wherein the method includes programming data stored in thefirst portion of the memory to the second portion of the memory uponconfiguring the second portion of the memory to operate as MLC memory.30. The method of claim 28, wherein the method includes programming datareceived in a command from a host to the first portion of the memoryupon configuring the second portion of the memory to operate as MLCmemory.
 31. The method of claim 27, wherein the method includesprogramming data to the first portion of the memory or the secondportion of the memory based on whether the entire first portion of thememory has data stored therein.
 32. The method of claim 31, wherein themethod includes programming the data to the second portion of the memoryupon the entire first portion of the memory having data stored therein.33. The method of claim 27, wherein the method includes: configuring thefirst portion of the memory to operate as a static SLC cache using acontroller of the memory; and configuring the second portion of thememory to operate as a dynamic SLC cache or MLC memory using thecontroller of the memory.
 34. The method of claim 27, whereinconfiguring the first portion of the memory to operate as a static SLCcache includes configuring the first portion of the memory to operate asa dedicated cache in SLC mode.
 35. The method of claim 27, whereinconfiguring the second portion of the memory to operate as a dynamic SLCcache includes configuring the second portion of the memory to operateas an overflow cache in SLC mode.
 36. An apparatus, comprising: amemory, wherein the memory includes: a first portion configured tooperate as a static single level cell (SLC) cache; and a second portionconfigured to operate as a dynamic SLC cache or multilevel cell (MLC)memory based on whether a quantity of blocks of memory cells used by thememory to program data stored in single level cells of the memory tomultilevel cells of the memory is equal to or greater than a quantity ofblocks of memory cells in the second portion of the memory.
 37. Theapparatus of claim 36, wherein the second portion of the memory isconfigured to operate as MLC memory upon the quantity of blocks ofmemory cells used by the memory to program data stored in single levelcells of the memory to multilevel cells of the memory being equal to orgreater than the quantity of blocks of memory cells in the secondportion of the memory.
 38. The apparatus of claim 36, wherein a size ofthe second portion of the memory corresponds to the quantity of blocksof memory cells used by the memory to program data stored in singlelevel cells of the memory to multilevel cells of the memory.
 39. Theapparatus of claim 36, wherein the memory includes a third portionconfigured to operate as MLC memory.
 40. The apparatus of claim 39,wherein: the first portion of the memory is configured to operate as thestatic SLC cache for an entire lifetime of the memory; and the thirdportion of the memory is configured to operate as MLC memory for theentire lifetime of the memory.